Enclosures are often used to house various electrical and electronic equipment such as controls, instruments, components, and the like in a wide range of different environments. The enclosures serve to limit access to the equipment as well as to protect the equipment against exposure to environmental contaminants such as dust, oil, water, and the like.
Typically, large-sized enclosures are provided with multi-hinged access doors that enable those working on the equipment to access various areas of the interior of the enclosure. The doors are fitted with the usual latch mechanisms that, when latched, secure the doors in a closed position and, when unlatched, permit the doors to be swung open. The main or "primary" access door is often tied to the control switch of the incoming power supply in such way that the primary door cannot be opened unless the power supply is switched "off".
Industry standards now also require that some means be in place to prevent the remaining "secondary" door or doors from being opened unless the primary door is first opened. In this way, none of the doors can be opened while the power is "on". This invention is directed to such a system for multi-door enclosures.